Lowered hydraulic chair base

ABSTRACT

A hydraulic chair base, for raising and lowering a dental chair, has a unitary pump-closed reservoir structure mounted thereon for delivering fluid to a fluid motor to raise the chair. Return of the fluid to the reservoir is controlled by a valve. Additionally, a catch sump is provided to capture fluid leakage from the fluid motor, from which catch sump the pump returns the fluid leakage to the reservoir, the catch sump also serving to capture any fluid in excess of the capacity of the closed reservoir.

United States Patent inventors John M. Gardella Matawan, NJ.; Anthony Ciavattoni, Staten Island, N.Y.; Karl Ileimur, Staten Island, N.Y. Appl. No. 879,279 Filed Nov. 24, 1969 Patented July 20, 1971 Assignee Pennwalt Corporation Philadelphia, Pa.

LOWERED HYDRAULIC CHAIR BASE 10 Claims, 8 Drawing Figs.

U.S. Cl 60/52 IID Int.Cl Fl5b 15/18 Field of Search 60/52 HD,

[56] References Cited UNITED STATES PATENTS 1,173,557 2/1916 Case 60/52 HD 1,959,682 5/1934 May 60/52 HD X 2,352,678 7/1944 Angell 60/52 l-ID X Primary Examiner- Edgar W. Geoghegan Attorneys-Carl A. Hechmer, Jr. and Earl T. Reichert PATENTEnJummsn 3.593521 SHEET 1 [IF 4 INVENTORS.

Fig 2 JOHN M. GARDELLA ANTHONY CIAVATTONI BY KARL HEIMUR ATTORNEY.

PATENTED JULEO an SHEET 2 OF 4 INVENTORS. JOHN M.G ELLA ANTHONY VATTONI BY KARL HEIMUR ATTORNEY.

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PATENTEU JUL 20 ml SHEET 3 [1F 4 INVENTORS. JOHN M. GARDELLA ANTHONY CIAVATTONI KARL HEIMUR 1 '7 ZKTKJL. Apr

ATTORNEY.

LOWERED HYDRAULIC CHAIR BASE This case relates generally to a chair base, but more particularly to a hydraulic chair base such as the type for raising and lowering dental chairs. Such a base is generally constructed so as to permit rotation of the dental chair about a vertical axis. The base usually includes a fluid source, a fluid motor operatively connected to the dental chair, means for delivering fluid from the fluid source to the fluid motor, and means for returning fluid from the fluid motor to the fluid source. This entire arrangement is generally mounted to rotate upon rotation of the dental chair.

The entire source of hydraulic fluid for operation of the dental chair is usually contained in an open sump disposed in the base of the chair. To raise the chair, the hydraulic fluid, usually oil, is delivered from the open sump to the fluid motor by actuating a pump. Lowering the chair is accomplished by returning the hydraulic fluid from the fluid motor to the open sump by actuating a valve.

This type of hydraulic chair base has always presented problems. The necessary slide structure for raising and lowering the dental chair is generally mounted upon a plate, which plate is adapted to rotate about a vertical axis. Because the dental chair is operatively connected to the slide structure, this arrangement permits rotation of the chair about a vertical axis. The open sump, which contains the entire source of hydraulic; fluid, is generally disposed directly below the'slide structure. Although the sump is comprised of a depression formed within the plate directly below the slide structure, this depression cannot be of a sufficient depth to contain all of the hydraulic fluid necessary for the operation of chair. Thus, it is necessary to surround the depression with an upwardly extending rim to generate the required sump capacity, upon which rim the slide structure is mounted. Thus, owing to the necessary height of this rim, the slide structure, and consequently the dental chair mounted thereon, is'higher than desired for optimum comfort of the dentist while working on a patient in an upright position. I

Also, during the installation or arrangement of the dental chair in the ofi'ice, there is a problem of oil spillage from the open sump onto the office floor during movement of the chair. The problem of oil spillage is even more acute, for example, where the hydraulic chair base is mounted on board ship, and thus subject to constant movement.

Also, due to the fact that the sump is open to the atmosphere, linting of the oil necessitates frequent oil changes. Consequently, a hydraulic chair base is needed which wilI'not only prevent linting and spillage of the oil, but will allow the dentist a more comfortable position while working on a patient in the upright position.

Therefore, one of the principal objects ofthe present invention is to provide a lower hydraulic chair base than was heretofore available.

Another object of the present invention is to provide a hydraulic chair base which will prevent oil leakage from the hydraulic system upon movement of the base.

Another object of the present invention is to provide a hydraulic chair base which will prevent linting or contaminating ofthe oil within the hydraulic system.

Another object of the present invention is to provide a hydraulic chair base that will protect against damage to the floor in the event that oil leakage from the hydraulic system does occur.

Another object of the present invention is to provide a hydraulic chair base which will return any leakage of the hydraulic fluid back into the hydraulic system.

Another object of the present invention is to provide a hydraulic chair base which, while rctuming oil leakage back into the hydraulic system, will not contaminate the system.

Another object of the present invention is to provide a hydraulic chair base which will return any oil leakage back into the hydraulic system simultaneously with the raising of the dental chair.

Another object of the present invention is to provide a hydraulic chair base which will capture any hydraulicfluid in excess of the capacity of the closed reservoir, which reservoir contains the sole source of hydraulic fluid.

Accordingly, the present invention seeks to accomplish such objects by providinga hydraulic chair base which includes a closed reservoir for containment of the hydraulic fluid supply, a fluid motor comprising a piston and a cylinder for raising and lowering the dental chair, arid means for delivering the hydraulic fluid between the fluid motor and the closed reservoir, the hydraulic chair base further having'a catch sump for. capturing any leakage from the fluid motor; the catch sump also sewing to capture'any hydraulic fluid in excess of the capacity of the closed reservoir.

Further objects and-advantages of the invention will be apparentfrom the detailed description below: In thedrawings:

FIG. I is a view on a small scale showing'generally a dental chair mounted upon a chair base;

FIG. 2 is an elevational view of a hydraulic chair base embodying the invention, with a cover assembly, shown in broken lines, enclosing the base;

FIG. 3 is a transverse sectional view taken along line 3-3 of FIG. 2,'showing a top view of a slide assembly, and .the-posi-' tion of a pump-closed reservoir structure;

FIG. 4 is a longitudinal sectional viewtaken along line 4-4 of FIG. 3, showing the position of a fluid motor and catch sump; I

FIG. 5 is a longitudinal sectional sectional view taken along line 5-5 of FIG. 4, showing details of a slide assembly; j

FIG. 6 is a longitudinal sectional view on an enlarged scale taken along line 66 ofFIG. 4, showing the packing assembly ofa fluid motor; 1, I Y m FIG. 7 is aflo'w'diagram showing thedircction of flow within the base hydraulic system'dtiring the raising of the chair;

FIG. 8 is a flow diagram showing the direction offlow within the base hydraulic system during the lowering of the chair.

Referring to FIG. 1 of the drawings, there is illustrated a dental chair I0 mounted upon a hydraulic chair .ba s 'e designated generally b'y'the numeral I2. The hydraulic chair base 12 embodying the present invention, and shown in detail in FIGS. 2 to 6, is enclosed by a bellows cover assembly designated by the numeral '14. The chair base 12 comprises a circular baseplate I6, the baseplate havinga cirul'arlwell 18 disposed therein, and the perimeter of the well I8 being defined by anupwardly extending rim20. I

Disposed within the'well I8 is a circular sump plate 22, having a generally circular depression 23 formed therein. An upwardly extendingridge 24 divides the depression 23 into two portions, one portion thereof defining a catch sunip 25. Partially surrounding the perimeter of depression 23'is an upwardly extending rim 26 for supporting the chair slide assembly as will be explained below,

The sump plate 22 has a plurality of roller bearings 28 mounted tothe periphery thereof. The roller bearings 28 are supported by rim 26, thus allowing rotation, about a vertical axis, of the suinp plate 22 within the well 18.

Rigidly mounted to the bottom of the catch sump25 is a stationary piston designated generally by thenurneral 30. As can be seen more clearly in FIG. 6, the piston 30 is c'o'r' n'prised of a piston rod 32, and a packing designated generally bythe .numeral 34. Dis posed within the center of piston rod 32 is a vertical passage 36. The packing 34 is comprised of two upwardly extending elastomeric sealing cups 38 and 40. A spacer member 43,disposed between the cups 38 and 40-, maintains the proper separation therebetween. Surrounding the piston 30 is a movably mounted cylinder 44 (closed at its upper end), the cylinder 44 being adapted to reciprocatever'tically with respect to the'piston 30. Together the piston 30 and cylinder 44 define a fluid motor designated generally by the numeral 45. Thus, as will be more fully explained later, as hydraulic fluid is delivered up through the vertical passage to the top of the packing 34 and into the cylinder 44, the cylinder 44 will move in an upward direction.

Rigidly connected the rim 26 and surrounding the ,fluid motor 45, is a stationary slide support member 46, having-a plurality of rollers 48 mounted thereon. Disposed within slide support member 46, and adapted to move over the rollers 48, is a slide member 50. The slide member 50 is rigidly connected to the cylinder 44, as indicated at 54. Thus upon vertical movement of the cylinder 44, slide member 50 moves vertically therewith over the rollers 48.

Disposed within the slide member 50 is a plunger 56. Plunger 56 is adapted to move vertically over the rollers 52 which are mounted within the slide member 50. The plunger 56 is supported entirely by chains 58 and 60, each of which is rigidly connected at one end thereof to the plunger 56, and at the opposite end thereof to the stationary slide support member 46 as indicated by the numerals 59 and 6] respectively. The chains 58 and 60 extend over rollers 62 and 64, which rollers are mounted on the movable slide member 50. Thus, it can be seen, that upon vertical movement of the slide member 50, plunger member 56, is constrained to move vertically therewith. Because the plunger member is supported entirely by the chains 58 and 60, each of which is rigidly connected at one end thereof to the stationary slide support member 46, the plunger 56 must necessarily move vertically with the slide member 50, because as the slide member 50 moves vertically, the rollers 62 and 64 will move therewith. Therefore, the chains 58 and 60 must necessarily travel over rollers 62 and 64, thereby moving plunger 56 in the same direction as the slide member 50. It is to be noted that plunger 56 must not only move in the same direction as slide member 50, but that it must move with respect thereto. The rate of movement of the plunger 56 with respect to the slide member 50 is a function of the diameter of rollers 62 and 64. I

Disposed adjacent the catch sump 25, and rigidly mounted to the sump plate 22 is a unitary structure 66, comprising a motor-driven pump, designated generally by the numeral 68, at one end thereof, and a closed reservoir designated generally by the numeral 70, at the other end thereof. The unitary structure 66 is a commercially available pump/reservoir unit available from the Tuthill Pump Company of Chicago, UL, listed as Model No. 30LT6839. Pump 68 include a pumping element which extends into reservoir 70, the reservoir containing the source of hydraulic fluid. The reservoir is in the form of a generally cup-shaped shell which is affixcd to pump 68, and surrounds the pumping element. Extending from the reservoir 70 is a passage 72 having a conventional check valve 74 disposed therein, which check valve 74 allows fluid to flow in only one direction, i.e., away from the reservoir 70. Passage 72 communicates with the vertical passage 36 disposed within the piston rod 32. Also connected to the reservoir 70 is a passage 76, which passage 76 communicates with the passage 72 at a point downstream from check valve 74. Passage 76 has disposed therein a conventional solenoid-operated valve 78 for controlling the flow therethrough, and a filter 79.

A third passage 80 extends between the sump and the reservoir 70. Disposed within the passage 80 is a filter 82, the filter being mounted adjacent the bottom ofv the sump 25. A conventional check valve disposed within the passage 80, allows fluid to flow in only one direction, i.e., from the sump 25, through the filter 82, and into the reservoir 70. A fourth passage 86, having disposed therein a conventional check valve 88, also extends between the sump 25 and the reservoir.

70. Check valve 88 allows fluid to flow in only one direction, i.e., from the reservoir 70 into the sump 25.

From the foregoing, and with reference to H68. 7 and FIG. 8, the operation of thehydraulic chair base will be described: When it is desired to raise the dental chair 10, the motordriven pump 68 is actuated. Upon actuation of the pump 68, fluid is delivered from the reservoir 70, through pump 68, through the check valve 74, and into the passage 72. Valve 78 being closed at this time, the fluid is delivered into the vertical passage 36 disposed within the piston rod 32, to the top of the piston 30, and into the cylinder 44, thus moving the cylinder 44 in an upward direction. The slide member 50, being rigidly connected'to the cylinder 44, as previously explained above, also moves in an upward direction, carrying with it the plunger 56 via chains 58 and 60, and thereby elevating the dental chair 10 which is suitably mounted to the plunger 56. Upon termination of the pumping action, the dental chair will be locked in an elevated position because valve 78, being closed, and check valve 74 allowing fluid to flow in only one direction, i.e., awayfrom structure 66', the hydraulic fluid is trapped within the cylinder 44.

It is to be noted that since the piston is rigidly mounted to the bottom of the catch sump 25, any leakage past the packing 34 will be trapped within the catch sump 25. During the raising of the chair, when the motor-driven pump 68 is actuated, a vacuum will be created within the reservoir 70. Due to the creation of this vacuum within the reservoir 70, it can be seen that any hydraulic fluid trapped within the catch sump 25 will be'returned to the reservoir 70 via filter 82, passage 80, and check valve 84. In the event there is no hydraulic fluid within the catch sump 25 during the raising operation, and due to the fact that the catch sump is exposed to atmospheric pressure, air will be pumped into the reservoir 70 to alleviate the vacuum created therein.

When it is desired to lower the chair, the solenoid-actuated valve 78 is opened, the weight of the chair forcing the hydraulic fluid through passage 36, into passages 72 and 76, through the filter 79 and valve 78, and back into the reservoir 70.

During the lowering operation, it is to be noted that upon returning the hydraulic fluid to the reservoir 70, any hydraulic fluid in excess of the capacity of the reservoir 70 will pass through the check valve 88, into the passage 86, and into the catch sump 25. Thus, it can be seen that the catch sump 25 not only serves to trap any leakage of hydraulic fluid past the packing 34, but also acts to capture any hydraulic fluid in excess of the capacity of the reservoir 70.

It can also be seen that with the provision of this closed hydraulic system, any linting or contamination of the hydraulic fluid within the system is prevented. Any air or hydraulic fluid pumped from the open catch sump 25, through the passage 80, and into the reservoir 70, passes through the filter 82, thereby eliminating any contamination of the hydraulic fluid within the closed hydraulic system. Also, hydraulic fluid returning from the fluid motor 45 to the reservoir 70 passes through the filter 79.

It has been possible with the arrangement just described to lower the dental chair by approximately 2%, thereby providing optimum comfort for the dentist while working on a patient in the upright position. As explained above, the main source of hydraulic fluid in present hydraulic chair bases is contained in an open sump disposed within the base. This open sump is usually located directly below the slide assembly, the sump being defined by an upwardly extending rim similar to the rim 26 of the present invention. The slide assembly is also mounted to this rim in the same manner as the present invention. Because the open sump contains the entire source of hydraulic fluid for the operationof the dental chair, it is necessary that the rim be sufficiently high to generate the required sump capacity. Thus, the dental chair is necessarily higher.

However, in the present invention the main source of hydraulic fluid is contained within the unitary structure 66 mounted adjacent the slide assembly. The catch sump 25, now situated below the slide assembly, serves only to capture leakage from the hydraulic system, or hydraulic system, or hydraulic fluid in excess of the capacity of the main closed reservoir 70 locatedwithin the unitary structure 66. Therefore, the upwardly extending rim 26 of the present invention is considerably lower than was previously possible, this rim now serving only as a mounting means for the slide assembly.

Although I have I described my invention with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example, and that numerous changes in the details of construction and combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.

What we claim is:

l. A hydraulic chair base for operating a dental chair comprising:

a. a base;

b. means defining a sump within said base;

c. a closed reservoir adapted to contain a source of fluid;

d. pump means operatively connected to said closed reservoir;

e. a fluid motor comprising a piston and a cylinder adapted to reciprocate with respect to each other, said fluid motor being vertically mounted within said sump;

. first passage means extending between said closed reservoir and said fluid motor, said first passage means being adapted'to deliver fluid from said closed reservoir to said fluid motor upon actuation of said pump means;

g. second passage means extending between said closed reservoir and said fluid motor, said second passage means having valve means disposed therein, and said second passage means being adapted to deliver fluid from said fluid motor to said closed reservoir upon actuation of said valve means;

h. a slide assembly operatively connected to said fluid motor, so constructed and arranged that upon actuation of said pump means, said dental chair is raised, and upon arrestment of said pump means and actuation of said valve means, said dental chair is lowered.

2. The combination claimed in claim 1 in which said pump means and said closed reservoir form a unitary structure, said unitary structure being mounted to said base, and adjacent to said sump.

3. The combination claimed in claim 2 including third passage means extending between said sump and said closed reservoir, so constructed and arranged that fluid leakage from said fluid motor to said sump, is delivered from said sump to said closed reservoir upon actuation of said pump means.

4. The combination claimed in claim 2 including fourth passage means extending between said closed reservoir and said sump, said fourth passage means being adapted to deliver fluid in excess of the capacity of said closed reservoir to said sump.

5. The combination claimed in claim 3 including fourth passage means extending between said closed reservoir and said sump, said fourth passage means being adapted to deliver fluid in excess of the capacity of said closed reservoir to said sump.

6. The combination claimed in claim 5 in which said piston comprises packing means and a piston rod, said piston rod being rigidly mounted to the bottom ofsaid sump.

7. The combination claimed in claim 6 in which said slide assembly comprises slide support means surrounding said fluid motor, and slide means operatively connected to said cylinder, said slide means being adapted to vertically reciprocate within said slide support means and adapted to be operatively connected to said dental chair.

8. The combination claimed in claim 7 including filter means disposed within said third passage means, and adjacent to the bottom of said sump.

9. The combination in claim 8 in which said base comprises a base member having a circular well disposed therein, and a sump member mounted for rotation within said well means about a vertical axis, said sump being disposed within said sump member, said slide assembly being rigidly mounted to said sump member, so constructed and arranged that said dental chair is adapted to rotate about said vertical axis.

10. The combination of claim 9 is which said unitary structure is rigidly mounted to said sump member.

qgggg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. U. S. 3, 593, 521 Dated Iuly 20, L971 Inventofls) Iohn M. Gardella. Anthony Ciavattoni and Karl Heimur It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

r- Column 2, line 29, "Fig. 5. is a longitudinal sectional sectional view taken along should read -FIG 5 is a longitudinal sectional view taken along Column 2, line 66 "member 43" should read member 42.

Column 3, line 5?, "conventional check valve disposed" should read -conventional check valve 84, disposed-- Column 4, line 62, "leakage from the hydraulic system, or hydraulic system," should read leakage from the hydraulic system,

Signed and sealed this 11th day of January 1972.

(SEAL) Attest:

" EDWARD M.PLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Acting Commissioner of Patents 

1. A hydraulic chair base for operating a dental chair comprising: a. a base; b. means defining a sump within said base; c. a closed reservoir adapted to contain a source of fluid; d. pump means operatively connected to said closed reservoir; e. a fluid motor comprising a piston and a cylinder adapted to reciprocate with respect to each other, said fluid motor being vertically mounted within said sump; f. first passage means extending between said closed reservoir and said fluid motor, said first passage means being adapted to deliver fluid from said closed reservoir to said fluid motor upon actuation of said pump means; g. second passage means extending between said closed reservoir and said fluid motor, said second passage means having valve means disposed therein, and said second passage means being adapted to deliver fluid from said fluid motor to said closed reservoir upon actuation of said valve means; h. a slide assembly operatively connected to said fluid motor, so constructed and arranged that upon actuation of said pump means, said dental chair is raised, and upon arrestment of said pump means and actuation of said valve means, said dental chair is lowered.
 2. The combination claimed in claim 1 in which said pump means and said closed reservoir form a unitary structure, said unitary structure being mounted to said base, and adjacent to said sump.
 3. The combination claimed in claim 2 including third passage means extending between said sump and said closed reservoir, so constructed and arranged that fluid leakage from said fluid motor to said sump, is delivered from said sump to said closed reservoir upon actuation of said pump means.
 4. The combination claimed in claim 2 including fourth passage means extending between said closed reservoir and said sump, said fourth passage means being adapted to deliver fluid in excess of the capacity of said closed reservoir to said sump.
 5. ThE combination claimed in claim 3 including fourth passage means extending between said closed reservoir and said sump, said fourth passage means being adapted to deliver fluid in excess of the capacity of said closed reservoir to said sump.
 6. The combination claimed in claim 5 in which said piston comprises packing means and a piston rod, said piston rod being rigidly mounted to the bottom of said sump.
 7. The combination claimed in claim 6 in which said slide assembly comprises slide support means surrounding said fluid motor, and slide means operatively connected to said cylinder, said slide means being adapted to vertically reciprocate within said slide support means and adapted to be operatively connected to said dental chair.
 8. The combination claimed in claim 7 including filter means disposed within said third passage means, and adjacent to the bottom of said sump.
 9. The combination in claim 8 in which said base comprises a base member having a circular well disposed therein, and a sump member mounted for rotation within said well means about a vertical axis, said sump being disposed within said sump member, said slide assembly being rigidly mounted to said sump member, so constructed and arranged that said dental chair is adapted to rotate about said vertical axis.
 10. The combination of claim 9 is which said unitary structure is rigidly mounted to said sump member. 